The invention relates to a type of combustion chamber ensuring high output, optimum fuel utilization and particularly low HC formation, besides very low CO and NOx figures. In order to achieve high output through good volumetric efficiency, the chamber below the valves must be empty also in the piston's upper dead center and must have no narrow channels to the combustion chamber. At the end of the expulsion of the waste gases and at the beginning of the attraction of a new gas mixture, the piston is in the area of the upper dead center. This means that the valves and the surface connecting both valves in the cylinder head must form a wall of the combustion chamber.
Another reason for this high output is that low CH values are attainable only if the combustion chamber is compact and has no fissured parts or channels such as from the combustion chamber to the valves. Thus it is also for this very important reason that one wall of the combustion chamber must consist of the two valves and the surface between them in the cylinder head.
The sole, but very important significance of the other design features of the combustion chamber, besides the deflection means for a rotary flow, is to be as compact as possible. The smaller the combustion chamber area relative to the volume, the better the fuel utilization and the smaller the HC percentages. It is precisely the specification of very low HC content in the exhaust gases in the future exhaust gas standards which constitutes the biggest problem, to be solved without costly and fuel-consuming measures such as afterburning or catalyst. Such alternate measures increase the cost of the engine by 20 to 25 percent and increase fuel consumption by 10 to 20 percent.
These figures indicate the importance and significance of the necessity of an absolutely compact combustion chamber, one wall of which is formed by the two valves and the surface between them.
Combustion chambers of this type are known. But in their present form they are still not in a position to bring about optimal exhaust gas and fuel consumption figures. In intermittent service, fuel with an octane rating ROZ=100 makes possible unobjectionable operation up to lambda 1.2 max. only, wherein NO is still very high at this setting. It is only at lambda 1.3 to 1.4 that NO drops far enough for these figures to be very low also.
It is an object of the invention to improve this compact combustion chamber through further measures so that CO and NO are reduced further; that the low HC is not increased, but rather decreased also, lowering fuel consumption and improving the output at the same time.